Image measuring system and methods of generating and executing non-stop image measuring program

ABSTRACT

The position of an imaging means relative to a measurement stage is moved based on a stage movement instruction input. The amount of light illuminating a work is adjusted by flashing strobe illumination at a certain cycle repeatedly and adjusting the pulse width of the strobe illumination based on an illumination adjustment instruction input. A part program is generated for image measurement including fetching positional information about the imaging means relative to the measurement stage and information about the pulse width of the strobe illumination based on a certain instruction input, irradiating the measuring object with strobe illumination of the pulse width passing through the position indicated by the fetched positional information and fetched at that position, and capturing instantaneous image information about the work.

CROSS REFERENCE TO RELATED APPLICATION

This application is based upon and claims the benefit of priority fromthe prior Japanese Patent Application No. 2005-164662, filed on Jun. 3,2005, the entire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an image measuring system and methodsof generating and executing a non-stop image measuring program, having anon-stop measurement mode for image measurement, in which an imagingmeans moves relative to a measuring object supported on a measurementstage and captures instantaneous image information at designatedmeasurement positions without making a stop.

2. Description of the Related Art

A conventional CNC image measuring machine comprises a measurement stagewhich is moved relative to an imaging means such as a CCD camera andstopped at a measurement position as shown in FIG. 12. Then the amountof illuminating light is adjusted to acquire image information about ameasuring object. To the acquired image information, image processingsuch as setting of a measuring tool and edge detection is applied,thereby executing a measurement at one measurement position. Thismeasurement is repeated as Measurement 1, Measurement 2, . . . and so onfor all measurement positions to achieve measurements at requiredpositions (hereinafter, such the measurement mode is referred to as a“standard measurement mode”).

In contrast, for the purpose of improving the throughput of measurement,a measurement may be performed without making a stop of the measurementstage relative to the imaging means even at a measurement position in ameasurement mode (hereinafter, such the measurement mode is referred toas a “non-stop measurement mode”). An image measuring machine havingsuch the non-stop measurement mode has been proposed (seeJP-A2004-535587, paragraphs 0005-0006, FIG. 2). This image measuringmachine irradiates the measuring object with strobe illumination, asshown in FIG. 13, without making a stop of the measurement stage atmeasurement positions. Alternatively, it captures instantaneous imageinformation imaged using a shuttered CCD camera, for image measurement.In the non-stop measurement mode, when the relation between the movementspeed of the stage and the strobe pulse width is appropriately set, afaster measurement can be achieved as an effect, without lowering themeasurement accuracy much.

In the conventional image measuring machine operative in the standardmeasurement mode, on teaching to generate a part program formeasurement, the measurement stage is manually moved to a measurementposition, followed by an illumination adjustment. Then, a measurementinstruction is given to set the measurement position and theillumination condition.

In the above-described non-stop measurement mode, however, imageinformation is captured as strobe-imaged while the measurement stage iskept moving relative to the imaging means at a measurement position.Accordingly, the conventional teaching method in the standardmeasurement mode that makes a stop at each measurement position for theillumination adjustment can not be applied to the non-stop measurementmode as it is. This is a problem.

The present invention has been made in consideration of such the problemand has an object to provide an image measuring system and methods ofgenerating and executing a non-stop image measuring program, capable ofgenerating or executing a measuring program in the non-stop measurementmode with a teaching method similar to the conventional one.

SUMMARY OF THE INVENTION

To achieve the above object, the present invention provides a method ofgenerating a non-stop image measuring program for image measurementincluding moving an imaging means relative to a measurement stagesupporting a measuring object while irradiating the measuring objectwith strobe illumination and capturing instantaneous image informationabout the measuring object at designated measurement positions withoutmaking a stop of the imaging means. The method comprises steps of:moving the position of the imaging means relative to the measurementstage based on a stage movement instruction input; adjusting the amountof light illuminating the measuring object by flashing the strobeillumination at a certain cycle repeatedly and adjusting the pulse widthof the strobe illumination based on an illumination adjustmentinstruction input; and generating the measuring program for imagemeasurement including fetching positional information about the imagingmeans relative to the measurement stage and information about the pulsewidth of the strobe illumination based on a certain instruction input,irradiating the measuring object while passing through the positionindicated by the fetched positional information, with the strobeillumination of the pulse width fetched at that position, and capturinginstantaneous image information about the measuring object.

The present invention also provides a method of executing a non-stopimage measuring program for image measurement including moving animaging means relative to a measurement stage supporting a measuringobject while irradiating the measuring object with strobe illuminationand capturing instantaneous image information about the measuring objectat designated measurement positions without making a stop of the imagingmeans. The method comprises executing the measuring program twicerepeatedly; executing, in the first execution, processing for moving theimaging means relative to the measurement stage along a path passingthrough the position indicated by plural pieces of positionalinformation described in the measuring program while irradiating themeasuring object with the strobe illumination and acquiringinstantaneous image information about the measuring object at theposition designated by the positional information; and executing, in thesecond execution, processing for reading the captured image informationand certain image processing to the read image information.

The present invention further provides a first image measuring systemhaving a non-stop measurement mode for image measurement includingmoving an imaging means relative to a measurement stage supporting ameasuring object while irradiating the measuring object with strobeillumination and capturing instantaneous image information about themeasuring object at designated measurement positions without making astop of the imaging means. The system comprises a means operative toenter a stage movement instruction, an illumination adjustmentinstruction and other certain instructions; a means operative to movethe position of the imaging means relative to the measurement stagebased on the entered stage movement instruction; a means operative toadjust the amount of light illuminating the measuring object by flashingthe strobe illumination at a certain cycle repeatedly and adjusting thepulse width of the strobe illumination based on the entered illuminationadjustment instruction; and a means operative to generate the measuringprogram for image measurement including fetching positional informationabout the imaging means relative to the measurement stage andinformation about the pulse width of the strobe illumination based onthe entered certain instructions, irradiating the measuring object whilepassing through the position indicated by the fetched positionalinformation, with the strobe illumination of the pulse width fetched atthat position, and capturing instantaneous image information about themeasuring object.

The present invention also provides a second image measuring systemhaving a non-stop measurement mode for image measurement includingmoving an imaging means relative to a a measurement stage supporting ameasuring object while irradiating the measuring object with strobeillumination and capturing instantaneous image information about themeasuring object at designated measurement positions without making astop of the imaging means. The system comprises a measuring programexecuting means operative for executing the measuring program twicerepeatedly in the non-stop measurement mode, executing, in the firstexecution, processing for moving the imaging means relative to themeasurement stage along a path passing through the position indicated byplural pieces of positional information described in the measuringprogram while irradiating the measuring object with the strobeillumination and acquiring instantaneous image information about themeasuring object at the position designated by the positionalinformation, and executing, in the second execution, processing forreading the captured image information and certain image processing tothe read image information.

In the method of generating a non-stop image measuring program and thefirst image measuring system according to the present invention, onteaching, the imaging means and the measurement stage have such apositional relation therebetween as relatively fixed at an imageacquisition position. In this state, the strobe illumination is flashedtoward the measuring object at a certain cycle repeatedly, and the pulsewidth is adjusted based on an entered instruction on the amount of lightwhile confirming the brightness of the image. In contrast, on executingthe measuring program, the strobe illumination is lightened based on theinformation about the adjusted pulse width, thereby acquiring imageinformation about the measuring object. Therefore, a non-stop imagemeasuring program can be generated through teaching with a methodsimilar to the standard measurement mode.

In the method of executing a non-stop image measuring program and thesecond image measuring system according to the present invention, themeasuring program is executed twice repeatedly. In the first execution,processing for moving the imaging means relative to the measurementstage and acquiring instantaneous image information at the designatedposition is executed. In the second execution, processing for readingthe captured image information and image processing are executedtogether. Therefore, the measuring program can be configured similar tothe conventional standard measurement mode. As a result, a measuringprogram for non-stop image measurement can be generated through teachingwith a method similar to the standard measurement mode.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an external perspective view showing a configuration of animage measuring system according to an embodiment of the presentinvention;

FIG. 2 is a functional block diagram of a computer in the same measuringsystem;

FIG. 3 is a flowchart showing a measurement procedure in a standardmeasurement mode;

FIG. 4 is a flowchart showing a measurement procedure in a non-stopmeasurement mode;

FIG. 5 is a flowchart showing generation of a measuring program and ameasurement procedure in the non-stop measurement mode in the system;

FIG. 6 shows a part program of an embodiment 1-1;

FIG. 7 is a flowchart showing processing for generating the part programof the embodiment 1-1;

FIG. 8 is a waveform diagram illustrative of illumination adjustmentcontrol of the embodiment 1-1;

FIG. 9 shows a part program of an embodiment 1-2;

FIG. 10 is a flowchart showing processing for generating the partprogram of the embodiment 1-2;

FIG. 11A shows a first execution portion of the part program of theembodiment 1-2;

FIG. 11B shows a second execution portion of the part program of theembodiment 1-2;

FIG. 12 illustrates measurement in the standard measurement mode; and

FIG. 13 illustrates measurement in the non-stop measurement mode.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments of the present invention will be described next based on theaccompanying drawings.

Embodiment 1

FIG. 1 is a perspective view showing an entire configuration of an imagemeasuring system according to an embodiment of the present invention.This system comprises a non-contact image measuring machine 1, acomputer system 2 operative to drive/control the image measuring machine1 and execute required data processing, and a printer 3 operative toprint out a measurement result.

The image measuring machine 1 is configured as follows. A table 11 isprovided and a measurement stage 13 is installed thereon to receive ameasuring object (hereinafter referred to as a work) 12 mounted thereon.The measurement stage 13 is driven in the Y-axis direction by a Y-axisdrive mechanism, not shown. Fixed at the central portion between bothedges of the table 11 are support arms 14, 15 extending upward. AnX-axis guide 16 is fixed to the support arms 14, 15 to link both upperends thereof. An imaging unit 17 is supported on the X-axis guide 16.The imaging unit 17 is driven along the X-axis guide 16 by an X-axisdrive mechanism, not shown. A CCD camera 18 is installed on a lower endof the imaging unit 17 as opposed to the measurement stage 13. Theimaging unit 17 contains an illuminator and a focusing mechanism, notshown, as well as a Z-axis drive mechanism operative to shift theposition of the CCD camera 18 in the Z-axis direction.

The computer system 2 includes a computer body 21, a keyboard 22, ajoystick box (hereinafter referred to as J/S) 23, a mouse 24, and adisplay unit 25. The computer body 21 realizes various functions asshown in FIG. 2 together with certain programs stored therein.

It includes a stage movement processor 31 for controlling the imagemeasuring machine 1 based on an instruction input from input means suchas the keyboard 22, the J/S 23 and the mouse 24; an illuminationadjustment processor 32; and an other measurement condition adjustmentprocessor 33. The stage movement processor 31 controls the XYS-axesdrive mechanisms in the image measuring machine 1 based on a stagemovement instruction input from input means to shift the position of theCCD cameral 18 relative to the measurement stage 13. At the time ofteaching, the illumination adjustment processor 32 flashes theilluminator in the image measuring machine 1 as a strobe light at acertain cycle successively and adjusts the pulse width of the strobelight based on an illumination adjustment instruction input from inputmeans. In a non-stop measurement mode, it flashes the strobe light witha predetermined pulse width at designated measurement positions. Theother measurement condition adjustment processor 33 adjusts othermeasurement conditions such as lens magnification and focusingadjustment based on instruction inputs for other measurement conditionadjustments.

The stage position, the information about the pulse width of the strobelight and the information about the other measurement conditionsadjusted at the processors 31-33 are fetched into a parameter input unit34 based on a certain instruction input from input means. The parameterfetched in the parameter input unit 34 is stored in a parameter memory35. A part program generator 36 uses the parameter stored in theparameter memory 35 to generate a part program for measurement. If inputmeans instructs a non-stop measurement mode, the part program generator36 generates a part program for the non-stop measurement mode. Thegenerated part program is stored in a part program memory 37.

A part program executor 38 is operative to read a required part programout of the part program memory 37 and execute it. In accordance withvarious commands described in the part program, the part programexecutor drives the stage movement processor 31, the illuminationadjustment processor 32, the other measurement condition adjustmentprocessor 33, an image acquisition unit 42 and an image processor 43appropriately. The pieces of image information imaged at the CCD camera18 are sequentially stored in an image memory 41. The pieces of imageinformation stored in the image memory 41 are sequentially displayed onthe display unit 25 and captured by the image acquisition unit 42 asstill images based on the part program. To the image informationacquired at the image acquisition unit 42, the image processor 43executes image processing for image measurement, such as setting of ameasuring tool, detection of edges, and detection of coordinates.

A measurement operation of the image measuring system according to theembodiment thus configured and a method of generating a part program aredescribed next.

FIG. 3 is a flowchart showing a procedure of image measurement in theconventional standard measurement mode. As shown, the image measurementin the standard measurement mode includes sequential executions of stagemovement, illumination setting, image acquisition and image processingin a procedure per measurement element. After completion of themeasurement at the position, the measurement position is moved to thenext to execute similar processing. Thus, the image measurement in thestandard measurement mode completes a measurement at each element (suchas a point measurement 1, a point measurement 2, . . . ).

To the contrary, in the non-stop measurement mode, measurementprocessing is separated into non-stop image acquisition and imageprocessing as shown in FIG. 4. In the non-stop image acquisition, whilethe position of the measurement stage 13 relative to the CCD camera 18is shifted along a measurement path that passes through each measurementposition, strobe illumination and image acquisition (and saving) aresuccessively executed for all measurement positions at an instance onpassing through the measurement position. After completion of all imageacquisitions, image processing is executed. In the image processing, theacquired and saved pieces of image information are read out one by one.In addition, image processing such as edge detection is successivelyexecuted for all measurement positions. The non-stop measurement moderequires no confirmation of a stop of the stage as in the standardmeasurement mode and accordingly can achieve a fast measurementoperation.

A flow of operation for such the non-stop image measurement is shown inFIG. 5.

First, a part program is generated through teaching in the non-stopmeasurement mode (S1), then the generated part program is employed toexecute a non-stop measurement (S2). Two methods can be considered toexecute the non-stop measurement shown in FIG. 4 through teachingsimilar to the conventional standard measurement mode. The first is sucha method (an embodiment 1-1) that adds a new function to the partprogram generation (S1) to make the part program itself configuredsuitable for the non-stop measurement while leaving the part programexecution (S2) itself almost same as the conventional one. The second issuch a method (an embodiment 1-2) that adds no particularly new functionto the part program generation (S1) itself and leaves the configurationof the part program almost same as the part program in the standardmeasurement mode. In this case, a new function is added to the partprogram execution (S2) to realize the non-stop measurement mode. The twomethods are described below individually.

Embodiment 1-1

FIG. 6 shows an example of a part program to be generated.

This part program comprises three subroutine blocks (Sub QVBlock_1,SubQVBlock_2, SubQVBlock_3). In the first subroutine block (SubQVBlock_1), instructions for setting a lens magnification andillumination are described in the first two lines, followed by movementpath commands instructing movement and strobe illumination and imageacquisition per measurement element. The second and third subroutineblocks (Sub QVBlock_2, Sub QVBlock_3) are measurement blocks.

The part program generator 36 operative to generate such the partprogram executes the following procedure.

(1) Among successive movement path commands, a movement path command forone measurement element and a corresponding image reading command and animage processing command (such as edge detection) are created inparallel in two subroutine blocks, respectively.(2) The commands shown in (1) are created corresponding to all paths.The image reading command and the image processing command (such as anedge detection command) are related to the movement path command throughcreation of anew subroutine block.(3) A measurement start command (StrobePath.Acquire: a non-stop imageacquisition command) is used to terminate a series of path generations.

This processing is specifically shown in FIG. 7.

First, whether a stage movement instruction is entered from input meansis determined (S11) and, if the stage movement instruction is entered,then stage drive processing is executed (S12). This allows the operatorto perform an operation for positioning the imaging range at ameasurement position.

Next, whether an illumination and other adjustment instruction isentered from input means is determined (S13) and, it the adjustmentinstruction is entered, then processing for adjusting the strobe pulsewidth and others is executed (S14). The strobe pulse may be generated insynchronization with a vertical synchronizing signal (VSync) for the CCDcamera 18. When the pulse width is widened from (1) to (2), an imagedisplayed on the display unit 25 can be lightened as a whole. When thepulse width is narrowed from (2) to (1), to the contrary, an imagedisplayed on the display unit 25 can be darkened as a whole. Therefore,the most appropriate amount of light may be determined visually throughdialog adjustment within 0-100% while confirming the image displayed onthe display unit 25. The strobe illumination may be realized with theuse of an LED or a xenon lamp.

Next, whether a measurement condition record instruction is entered isdetermined (S15) and, if the record instruction is entered, then themeasurement condition is recorded in the first subroutine block (SubQVBlock_1) (S16). In the example of FIG. 6, lens and illuminationsettings are recorded in the beginning of “Sub QVBlock_1”.

Subsequently, whether a measurement instruction is entered is determined(S17) and, if the measurement instruction is entered, then positionalinformation indicative of a current position of the measurement stage 13relative to the CCD camera 18 is recorded in “Sub QVBlock_1” asinformation about the movement position (S18). In addition, a newsubroutine block is created and an image information reading command andan image processing command corresponding to the above information aboutthe movement position are recorded in the new subroutine block (S19).

The above steps are repeated until a measurement start is instructed(S20). If the measurement start is instructed, then a measurement start(image acquisition) command is recorded in “Sub QVBlock_1” (S21),followed by terminating the processing.

In such the on-line teaching, the operator shifts the position of themeasurement stage 13 relative to the CCD camera 18 to ameasurement-intended position, and fixes the CCD camera 18 and themeasurement stage 13 on that position. The operator then setsmeasurement conditions, for example, by focusing and adjusting theamount of light while confirming the display screen of the display unit25, and enters a measurement instruction, thereby acquiring parametersrequired for the non-stop measurement at that position. As a result,through a teaching operation almost same as the on-line teaching in theconventional standard measurement mode, teaching in the non-stopmeasurement mode can be performed.

On execution of the part program thus generated, the generated partprogram is sequentially executed. In this case, the part programexecutor 38 may be configured almost similar to the conventional one.

Embodiment 1-2

In the embodiment 1-1 the part program itself is configured suitable forthe non-stop measurement. To the contrary, in an embodiment 1-2 the partprogram itself is almost same as that in the standard measurement modewhile processing in the part program executor 38 is different from theconventional one.

FIG. 9 shows a part program according to the embodiment 2.

The part program includes a command for switching to the non-stopmeasurement mode described in the beginning, and a command for switchingto the standard measurement mode described in the tail. The part programcomprises three subroutine blocks (Sub QVBlock_1, Sub QVBlock_2, SubQVBlock_3), like the embodiment 1. In the first subroutine block (SubQVBlock_1), instructions for setting measurement conditions such as alens magnification and illumination are described. In the second andthird subroutine blocks (Sub QVBlock_2, Sub QVBlock_3), described permeasurement unit are commands of movement to the measurement positionand strobe illumination and image acquisition, and image reading,measurement condition setting, image processing (edge detection), andmeasurement end.

This part program is generated almost in the following procedure.

(1) The time to start recording the part program is similar to theconventional standard measurement mode.

(2) The command for switching from the standard measurement mode to thenon-stop measurement mode is selected and executed.

(3) In the non-stop measurement mode, through a series of stage movementcommands (successive paths), stage movement, strobe pulse lightening andimage acquisition at the time of strobe lightening are executed. Theimage at the time of strobe lightening is made to contain informationabout the stage position latched at the time of strobe lightening.(4) After a series of stage movements, the images at the times of strobelightening are read out place by piece for use in execution of imageprocessing such as edge detection.(5) After completion of all processing, the command for switching fromthe non-stop measurement mode to the standard measurement mode isexecuted.

The processing is specifically shown in FIG. 10.

Different from the flow of the embodiment 1 shown in FIG. 7, a commandfor switching to the non-stop measurement mode is recorded in thebeginning (S31). In addition, if the measurement is instructed (S17), anew subroutine block is created, and a movement position, an imagereading command and an image processing command per measurement unit arerecorded (S32). Further, if the measurement start is instructed (S20),an image acquisition command and a command for switching to the standardmeasurement mode are recorded (S33). Other points including theillumination adjustment are similar to those in the embodiment 1.

The generated part program is executed as follows. The part programexecutor 38, on detection of the command for switching to the non-stopmeasurement mode in the beginning of the part program, repeatedlyexecutes the processing twice, which lasts to the step immediatelybefore the command for switching to the standard command. In this case,in the first execution, only the portions shown with bold characters inFIG. 1A, that is, the portions including measurement condition setting,movement position recording and non-stop image acquisition are executed.In the second execution, only the portions shown with bold characters inFIG. 11B, that is, the portions including image reading and imageprocessing are executed.

It is possible even for such the part program generating method togenerate a part program through teaching similar to the conventionalone.

1. A method of executing a non-stop image measuring program for imagemeasurement including moving an imaging means relative to a measurementstage supporting a measuring object while irradiating the measuringobject with strobe illumination and capturing instantaneous imageinformation about the measuring object at designated measurementpositions without making a stop of the imaging means, the methodcomprising: executing the measuring program twice repeatedly; executing,in the first execution, processing for moving the imaging means relativeto the measurement stage along a path passing through the positionindicated by plural pieces of positional information described in themeasuring program while irradiating the measuring object with the strobeillumination and acquiring instantaneous image information about themeasuring object at the position designated by the positionalinformation; and executing, in the second execution, processing forreading the captured image information and certain image processing tothe read image information.
 2. The method according to claim 1, furthercomprising steps of generating the non-stop image measuring program, thesteps including: moving the position of the imaging means relative tothe measurement stage based on a stage movement instruction input;adjusting the amount of light illuminating the measuring object byflashing the strobe illumination at a certain cycle repeatedly andadjusting the pulse width of the strobe illumination based on anillumination adjustment instruction input; and generating the measuringprogram for image measurement including fetching positional informationabout the imaging means relative to the measurement stage andinformation about the pulse width of the strobe illumination based on acertain instruction input, irradiating the measuring object whilepassing through the position indicated by the fetched positionalinformation, with the strobe illumination of the pulse width fetched atthat position, and capturing instantaneous image information about themeasuring object.
 3. The method according to claim 2, the step ofgenerating the measuring program including steps of recording thepositional information in a first subroutine block every time thepositional information is fetched, and creating a new subroutine blockto record in the new subroutine block an image read command and an imageprocessing command corresponding to the positional information, andrecording on receipt of a measurement start instruction a command forinstructing image acquisition start behind a series of the positionalinformation in the first subroutine block.
 4. The method according toclaim 2, the step of generating the measuring program including steps ofrecording at the beginning of the program a command for switching to anon-stop measurement mode, creating a new subroutine block every timethe positional information is fetched and recording the positionalinformation in the created subroutine block, and recording in thesubroutine block an image read command and an image processing commandcorresponding to the positional information, and recording on receipt ofa measurement start instruction a command for instructing imageacquisition start behind a final subroutine block.
 5. An image measuringsystem having a non-stop measurement mode for image measurementincluding moving an imaging means relative to a measurement stagesupporting a measuring object while irradiating the measuring objectwith strobe illumination and capturing instantaneous image informationabout the measuring object at designated measurement positions withoutmaking a stop of the imaging means, the system comprising a measuringprogram executing means operative for executing the measuring programtwice repeatedly in the non-stop measurement mode, executing, in thefirst execution, processing for moving the imaging means relative to themeasurement stage along a path passing through the position indicated byplural pieces of positional information described in the measuringprogram while irradiating the measuring object with the strobeillumination and acquiring instantaneous image information about themeasuring object at the position designated by the positionalinformation, and executing, in the second execution, processing forreading the captured image information and certain image processing tothe read image information.